Download Answers to pgs. 143 - 144 wks.

Name
Class
Date
Directed Reading B continued
9. What hypothesis did Darwin develop about the Galápagos finches?
Darwin hypothesized that the island finches descended from South
American finches. He proposed that the first finches on the islands
were blown there from South America by a storm. His hypothesis is
that the finches evolved adaptations for the various island
environments over many generations.
Match the correct description with the correct term. Write the letter in the space
provided.
Malthus's
______
principle
Lyell's theory
______
selective
______
breeding
10. the idea that human populations can grow
faster than the food supply
a. Lyell’s theory
b. selective breeding
c. Malthus’s principle
11. the idea that Earth had formed naturally
over a long period of time
12. the practice of breeding plants and animals
to have desired traits
13. Why do farmers and breeders use selective breeding?
farmers and breeders can get more money by selling
crops and livestock with desired traits.
Ex. bigger tomatoes, and cuter puppies and cows with more meat on them
14. Why might selective breeding be used in horses?
Horses with a better pedigree with desired traits are selected to breed
so that the next generations of horses will be stronger and faster, especially
in a time without cars and tractors.
15. Why might selective breeding be used in fruit trees?
Trees that make bigger fruit faster, will be bred so that whole crops
will have a higher annual yield. This makes more money for farmers
and can reduce the price of fruit.
16. After reading Malthus’s theory, Darwin realized that any species can
produce many
offspring
.
17. The populations of all species are limited by starvation, disease, predation,
or
competition
.
18. Darwin reasoned that survivors had traits that helped them
survive
in their environment.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Life Science
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143
The Evolution of Living Things
Name
Class
Date
Directed Reading B continued
19. Darwin believed that offspring of these survivors inherit
the
traits
that help them survive.
20. What idea of Darwin’s about species was supported by Charles Lyell’s book?
Darwin reasoned that if Earth were very old, then there would be
enough time for organisms to slowly change.
DARWIN’S THEORY OF NATURAL SELECTION
21. What was the name of Darwin’s famous book?
The Origin of Species
22. What theory did Darwin introduce in the book?
The theory of natural selection.
23. What is natural selection?
Natural selection is the mechanism, or process by which organisms that are
better adapted to their environment survive and reproduce more successfully
that less well adapted organisms do.
It is also known as "Survival of the fittest"
Match the correct description with the correct step in natural selection. Write the
letter in the space provided.
overproduction
______ 24. Many more offspring are produced than
will survive.
inherited variation
successful
______
reproduction
b. struggle to survive
c. overproduction
______ 25. No two offspring are alike.
struggle to survive
______
a. inherited variation
26. Many offspring will be killed before
reproducing.
d. successful reproduction
27. The best adapted organisms will have
many offspring that survive.
28. List two things that Darwin did not know in relation to his theory.
1. Darwin did not know what the source of the variation in traits was,
Now we know that it is genetic mutation.
2. Darwin did not know how organisms inherited traits,
Now we know it is through replication and meiosis and fertilization.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt California Life Science
19
144
The Evolution of Living Things